text: #ifndef RTC_H
  #define RTC_H
  
  #include "struct.h"
  
  namespace RTC
  {
      RetResult init();
  
      RetResult sync();
  
      uint32_t get_timestamp();
  
      float get_external_rtc_temp();
  
      uint32_t get_last_sync_tick();
  
      void print_time();
      void print_temp();
  
      bool tstamp_valid(uint32_t tstamp);
  
      // TODO: Temp public
      RetResult sync_gsm_rtc_from_ntp();
      RetResult sync_time_from_gsm_rtc();
      RetResult sync_time_from_http();
      RetResult sync_time_from_ext_rtc();
      RetResult init_external_rtc();
      RetResult set_external_rtc_time(uint32_t timestamp);
      RetResult set_system_time(uint32_t timestamp);
  
      uint32_t get_external_rtc_timestamp();
      // TODO: up to here
  }
  
  #endif